Introduction: Primary dysmenorrhea is one of the most commonly reported symptoms in 50% of adolescent girls. The aim of this study was to determine the effect of Lavender essential oil on severity of pain and symptoms of primary dysmenorrheal.

Methods : In this randomized clinical trial, 60 students with primary dysmenorrhea which had pain score greater than 5 based on a 10 point visual analogue scale were randomly divided into two groups. Experimental group did the massage with essential oil of Lavender (2 drops in 2.5 cc of almond oil) and placebo group with 2.5cc almond oil only, 48 hours before and after menstruation. Massage was done 15 minutes twice a day for two menstrual cycles above pubis. Samples recorded their pain severity and menstrual symptoms, before intervention and two cycles after the intervention. Data collection tools were a menstruation information record form and pain visual analogue scale. T-test, Chi-square and Fisher's exact test were used for data analysis.

Results: Before the intervention, there was not a significant difference in the two groups in pain severity and systemic symptoms of dysmenorrheal. Mean pain severity of dysmenorrhea was reduced in two cycles after of intervention comparing to the placebo group (p<0.001). There was significant differences between experimental and control groups in the frequency of systemic symptoms of dysmenorrhea (back pain, abdominal pain, nausea and fatigue) (p<0.05).

Conclusion: Using Lavender aromatherapy massage is effective in decreasing the severity of menstrual pain and systemic symptoms. Aromatherapy can be offered as part of nursing care to women experiencing primary dysmenorrhea.